Is it harmful for teeth to use listerine ( fluoride mouthwash) ?

Not at all: Listerine contains antibacterial ingredients, and the fluoride is the best thing to prevent cavities. Use only as directed on label. Do not overuse. Mouthwash does not replace either brushing or flossing. Brush 2x/day for 65-70% bacteria removal. Floss 1x/day to remove 25-30% of bacteria from between teeth where toothbrush can't reach. Use mouthwash 1x/day to remove 1-2% of bacteria.